crane



(No Model.) 2 Sheets-Sheet 2.

A. S. CRANE.

GOMPENSATING PENDULUM.

No. 288,027. Patented Nov. 6, 1883.

WITNESSES: OR:

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COMPENSATING 'PENDULUM.

SPECIFICATION forming part of Letters Patent No. 28?,02'7, dated November 6, 1883.

Application filed January 29,1833. (X0 model.)

To all Lu/ 2 0771 it may concern.-

Be it known that I, AUcUsTUs S. CRANE, a citizen of the United States, residing at Newark, in the count-y of Essex and State of New Jersey, have invented certain new and useful Improvements in Compensating Pendulums, of which the following is a specification.

The object of my invention is to produce a reliable and accurately adjustable compensating pendulum, which shall compensate throughout its entire length. To this end my pendulum has-but three rods, the compensation being effected by means of lovers, and the degree of compensation being adjustable by shifting he fulcra of these levers.

Figure l of the accompanying drawings is a front elevation of the preferred form of my pendulum on a reduced scale, part of the bob being broken away. Fig. 2 is a fragmentary front elevation thereof on a larger scale, partly in section. Fig. 3 is a fragmentary side elevation of Fig. 2. Fig. 4 is a horizontal section cut in the plane of the line 4 4 in Fig. 2. Fig. 5 is a diagram, and Figs. 6, 7, and 8 are fragmentary front elevations illustrating modifications.

Let A designate the center rod, and B Bthe two side rods. These are all fixed to a crosshead, 0, at the top, and this cross-head is suspended by a leafspring, a, as usual.

I) is the pendulum bob or ball, which is made in two parts, or consists of two disks, :1 d, as best shown in Fig. Between these disks are the compensatirig-levers. Two levers, E E, are jointed together, and to the bottom end of the rod A at c, and extend thence laterally, and to each lever E the lower end of one of the rods B is fulerumed. These fulcra are lettered b b. The outer ends of the levers E E are connected to the bob 1) by means of links F F. A bolt, 0, joints the links F F together and connects the two disks (2 d.

The rods A and B B maybe of any material having different coefficients of expansion by heat, provided that the red A expands more rapidly than the rods B B. The rods B B should be both alike and of the same material. In Figs. 1 to 3 they are shown as made of wood, in which case the red A may be made of steel or any metal; but I prefer to make the rods B B of steel and the red A of brass. As the temperature rises the rod A expands to a greater extent than the rods B B, and hence its lower end descends more rapidly, thereby tilting the levers E E, causing their outer ends to rise and separate, and straightening out the linksF F, thereby lifting the point e and the pendulum-bob.

Vith the fulcra b I) in the positions shown in Fig. 2, the ratio of expansion of the rods A and B B should be approximately as four to three. Any other ratio of expansion may be compensated for by placing the fulcra b b at different points. If the ratio of expansion of the bars and the center of gravity of the entire pendulum were accurately known the exact position for these fulcra might be ascertained by calculation; but as such cannot be the casein practice, I render the fulcra adjustable by forming the levers E E with 1011- gitudinal slots f f at any point along which the fulcruming-bolts may be set, their proper position being ascertained by experiment. Each lever E is formed with a deep groove in its upper side, extending beneath the slot f. The lower end of the rod 6 is made thin enough to easily enter this slot, sov that the small fulcruming-bolt b can be tightened against the sides of the lever E, without impairing the freedom of movement of the joint.

The adjustment of the fulcra should be such that the center of gravity of the pendulum will always be kept at the same distance from the point of suspension. In the diagram, Fig. 5, the center 6 is assumed to be the center of gravity, though in reality the true cen ter of gravity would be somewhat above this. The full lines show the positions of the centers of the levers and links in cold weather, and the dotted lines show the same in warm weather, the extent of movement being somewhat exaggerated for the sake of illustration. It will be observed that the center 6 remains always at the same height.

For very accurate and expensive clocks or regulators it may be preferable to use the construction shown in Fig. 6, where screws 9 g are substituted for the slots, and the rods B B are pivoted to nuts 71. h. By turning these screws the fulcra are adjusted.

My pendulum has the advantage that there is no dead or non-compensating portion, except the length of, the springv a and the vertical thickness of its block and the cross head 0, and consequently a change of temperature affecting only a portion of the length of I the pendulum will be compensated for as accurately as a change affecting its entire length. Its superiority in this respect over the ordinary grid-iron and mercurial, pendulums must be manifest. Another advantage is that but three rods are required, whereby excessive weight is avoided, and also that the degree of compensation is accurately adjusta ble.

The efiective length of the pendulum is adjusted, in order to regulate .the speed of the clock, preferably by lengthening or shortening the rod A, as shown best in Fig. 2. The rod is divided into two parts, the lower portion of which is also lettered A. The upper end of the portion A is fastened to a cup-shaped nut, G, in such manner that the latter may freely turn upon it, and the lower end of the upper portion of the rod is screw-threaded and screws into the nut. By turning this nut the rod A is lengthened, and with the proportions shown its lengthening need be onlyslightly more than one-quarter. of the required vertical adjustment of the pendulum-bob, owing to the multiplication of the motion through the levers E E and links F F.

The jointed links F F may be dispensed with, if desired, by substituting for them a cross-bar, F, as shown in Fig. 7, to whichthe bob D is fastened. The ends of the levers E freedom of motion to the parts. The crossbar also may be dispensed with by adopting the construction shown in Fig. 8, where four bars are used, and the two bars A A (being the bars of greatest expansion) are placed outside of the bars B B. The levers E E are jointed together and to the bolt D at 0.-

Instead of adjusting the compensation by shifting the fulcra b b, the joints 0 or the joints between the levers E and links F may be slotted or adjustable.

I make no claim to a compensating pendulum having three or more rods, with levers 'for imparting an inverse'movement .to the expansion by heat than the others, two levers jointed to the lower end of the middle rod, and eachjointed tothe lower end of one of the other rods, and a single bob connected to the free ends of both said levers in such manner as to retain its central position during their 'movement, substantially as set forth.

3. A single centrally-arranged bob consist-- ing of two parallel disks fixed on the same axis, two levers arranged between said disks, their free ends connected to said axis, and each lever jointed to the lower ends of two pendulum-rods of different degrees of expansion by heat, in combination with said rods, substantially as set forth.

4. The combination of cross-head O, rods A, and B B, levers E E, jointed together and to said rod A, and fulcrumed to said rods B B- by adjustable fulcra, and bob D, connected to said levers, substantially as set forth.

ulum, of rods A and B B, levers E E, links F F,

' and bob D, substantially as set forth.

6. The combination ofrods B B, divided rod A, adjusting-nut G, levers E E, and bob D,

connected to said levers, substantially as set forth.

- In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

AUGUSTUS S.- CRANE.

Witnesses:

ARTHUR O. Fnilsnn, HEN-RY CoNNn'r'r.

5. The combination, in a compensating pend- 

